On 11/18/20 11:59 AM, Gregory Etelson wrote: > Hello Andrew, > >> On 11/17/20 10:18 PM, Gregory Etelson wrote: >>> There is a discrepancy between RTE ETHDEV API and flow rules guide >>> regarding flow rules maintenance after port stop. RTE ETHDEV API in >>> librte_ethdev.h declares that flow rules will not be stored in PMD >>> after port stop: >>> >>>>> Quite start >>> Please note that some configuration is not stored between calls to >>> rte_eth_dev_stop()/rte_eth_dev_start(). The following configuration >>> will be retained: >>> >>> - MTU >>> - flow control settings >>> - receive mode configuration (promiscuous mode, all-multicast mode, >>> hardware checksum mode, RSS/VMDQ settings etc.) >>> - VLAN filtering configuration >>> - default MAC address >>> - MAC addresses supplied to MAC address array >>> - flow director filtering mode (but not filtering rules) >>> - NIC queue statistics mappings >>> <<<< Quote end >>> >>> PMD cannot always correctly restore flow rules after port stop / port >>> start because application may alter port configuration after port stop >>> without PMD knowledge about undergoing changes. Consider the >>> following scenario: >>> application configures 2 queues 0 and 1 and creates a flow rule with >>> 'queue index 1' action. After that application stops the port and >>> removes queue 1. >>> Although PMD can implement flow rule shadow copy to be used for >>> restore after port start, attempt to restore flow rule from shadow >>> will fail in example above and PMD could not notify application about >>> that failure. As the result, flow rules map in HW will differ from >>> what application expects. In addition, flow rules shadow copy used >>> for port start restore consumes considerable amount of system memory, >>> especially in systems with millions of flow rules. >>> >>> Signed-off-by: Gregory Etelson <getel...@nvidia.com> >>> Acked-by: Ori Kam <or...@nvidia.com> >>> --- >>> doc/guides/prog_guide/rte_flow.rst | 5 ++--- >>> 1 file changed, 2 insertions(+), 3 deletions(-) >>> >>> diff --git a/doc/guides/prog_guide/rte_flow.rst >>> b/doc/guides/prog_guide/rte_flow.rst >>> index 944e8242d6..dfe5a40f8e 100644 >>> --- a/doc/guides/prog_guide/rte_flow.rst >>> +++ b/doc/guides/prog_guide/rte_flow.rst >>> @@ -3055,10 +3055,9 @@ Caveats >>> temporarily replacing the burst function pointers), an appropriate >> error >>> code must be returned (``EBUSY``). >>> >>> -- PMDs, not applications, are responsible for maintaining flow rules >>> +- Applications, not PMDs, are responsible for maintaining flow rules >>> configuration when stopping and restarting a port or performing >>> other >>> - actions which may affect them. They can only be destroyed >>> explicitly by >>> - applications. >>> + actions which may affect them. >>> >>> For devices exposing multiple ports sharing global settings affected >> by flow >>> rules: >>> >> >> Re-reading it, it still looks vague. What happens on: >> - port stop without removal of flow rule before >> - port close without removal of flow rules before >> - port reset (which could be stop/start, e.g. to recover from error >> condition) > > PMD should remove all flows related to hardware resource that was invalidated.
Stop? Close? I agree and documentation should say so in a bit clear way.
